WATER PRODUCTIVITY OF IRRIGATED AGRICULTURE IN INDIA ...

WATER PRODUCTIVITY OF IRRIGATED AGRICULTURE IN INDIA:
POTENTIAL AREAS FOR IMPROVEMENT
M. Dinesh Kumar 1 , O.P. Singh 2 , Madar Samad 3 , Hugh Turral 4 and Chaitali Purohit 5
Abstract
The objective of the study is to explore the scope for water productivity enhancement in irrigated agriculture
in India through: i] water control; ii] optimizing nutrient input to crop; iii] improving the quality and reliability of
irrigation water; and, iv] growing crops in regions where climate is favourable. The study is based on data from three
important river basins in India, viz., Indus, Narmada and Sabarmati. The study involved: 1] estimating the incremental
water productivity of selected crops viz., wheat and cotton in response to applied water, and fertilizer dosage; 2]
estimating water productivity of the same crop across agro-ecological zones within the basin, and 3] comparing
determinants of crop water productivity with different sources of irrigation with differential reliability and quality.
Most farmers are applying water within a regime where the yield response to both irrigation and fertilizer
dosage is positive. Also, their water application corresponds to a regime where water productivity (Rs./m 3 ) response
to irrigation is negative and fertilizer is positive. But, in certain situations, farmers’ water application regime
corresponds to a regime where both yield and water productivity responses to irrigation are either positive or
negative. Within basins, for the same crop, water productivity in both physical and economic terms is much higher in
high rainfall, sub-humid area as compared to that in low rainfall, arid areas. The quality and reliability of irrigation
can significantly impact the type of crops chosen by farmers and the crop yield, thereby raising water productivity.
There is ample scope for improving water productivity in irrigated agriculture through water control. But, in
most cases, it may lead to reduced net return per unit of land. Hence, they would have incentive to go for water control
measures only if there is sufficient land, which can be put to use for irrigated production using the saved water.
1. INTRODUCTION
Economic value of water in agriculture is much lower than that in other sectors (Barker et al., 2003),
including manufacturing (Xie et al., 1993). Growing physical shortage of water on the one hand, and scarcity of
economically accessible water owing to increasing cost of production and supply of the resource on the other,
had preoccupied researchers with increasing productivity of water use in agriculture in order to get maximum
production or value from every unit of water used (Kijne et al., 2003).
Raising water productivity is the cornerstone of any demand management strategy. Definition of water
productivity is scale dependent. Water productivity can be analyzed at the plant level, field level, farm level,
system level and basin level, and its value would change with the changing scale of analysis (Molden et al.,
2003). The classical concept of irrigation efficiency used by water engineers omitted economic values and
looked at the actual evapo-transpiration (ET) against the total water diverted for crop production (Kijne et al.,
2003). Moreover, it does not factor in the “scale effect” (Keller et al., 1996).
At the field level, there is no single parameter to determine the efficiency of water use in crop
production. Measures to enhance yield to raise water productivity in biomass per unit of water depleted, might
increase the cost of production thereby reducing net return per unit of water depleted. Therefore, crop water
productivity needs to be assessed in terms of both kilogram of crop per cubic metre of water diverted or depleted
(Kg./m 3 ); and net or gross present value of the crop produced per cubic metre of water (Kijne et al., 2003).
1
Researcher and ITP Leader, International Water Management Institute, Patancheru, Andhra Pradesh, India; E-mail: d.kumar@cgiar.org
2
Agricutural Economist, Department of Agricultural Economics, Institute of Agricultural Sciences, Banaras Hindu University,
Varanasi – 221 005, E-mail: singhop@bhu.ac.in ; ompsingh@gmail.com
3
Principal Researcher and Head India Office, International Water Management Institute
4
Formerly Principal Scientist, IWMI, Sri Lanka
5
Formerly Junior Consultant, IWMI, India
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While the yield would increase with an increase in actual ET, the water productivity (Rs./m 3) would start
leveling off and then start declining much before the yield reaches maximum (see for instance Molden et al.,
2003). The reason is that the amount of depleted water might increase with increase in irrigation dosage, and
beyond a point, it does not result in yield increase (Vaux and Pruitt, 1983). Similarly, while the yield would keep
increasing until a point with increase in nutrient inputs, the net return might start decreasing even at level of
nutrient dosage lower than that corresponding to maximum yield. Hence, the challenge is to identify optimum
level of water and nutrient inputs to ensure maximum return per unit of land and water. The measure can be
referred to as “water control”; and optimizing nutrient dosage, respectively.
“Water control” refers to supplying water dosages close to the difference between crop water requirement
and available soil moisture in the root zone. It ensures greater utilization of applied water for ET, and
minimal non-recoverable percolation from the applied water, which is non-beneficial. It also reduces the fraction
of non-beneficial evaporation from applied water. Hence, with controlled water delivery, the yield would be more
for the same depletion or consumed fraction, resulting in higher water productivity. 1 The measures for this
include on-farm water management practices and improving the conveyance of water. Micro irrigation systems
take care of water control for many crops, and in certain other crops by farm leveling.
Crop water productivity also depends on the reliability and quality of irrigation water applied in addition
to control over water delivery. Improved reliability can ensure better timing of irrigation to ensure crop growth
needs (Meinzen-Dick, 1995). With the same amount of water applied, the crop consumptive use (ET) would
change depending on the timing of water application. On the other hand, non-availability of moisture at critical
stages of crop growth can significantly reduce the crop growth and yield and the reduction would not be
proportional to the reduction in water applied or water consumed. Therefore, the quality and reliability of irrigation
should affect water productivity, with the same amount of irrigation water applied. 2
Now, opportunities for enhancing water productivity would change when one moves from the field to
the basin. Enhancing water productivity at the field through water control may adversely affect the availability of
water for downstream uses in a closed basin. The reason is the probable reduction in non-consumptive part of
the water applied (Allen et al., 1998; Molle and Turral, 2004). If those downstream uses have higher return per
unit water use, water control measures would result in productivity losses at the basin level. On the other hand,
at the basin level, as Abdulleev and Molden (2004) note, opportunities might exist for growing the same crop in
areas where their ET values are lower, which result in improved water productivity in both physical and economic
terms. Hence, crop water productivity needs to be mapped across different agro climates in the basin.
In this paper, the potential for enhancing water productivity in agriculture and water saving are explored
in selected river basins of India through the following measures: 1] water control and optimizing nutrient input to
crops; 2] improving the quality and reliability of irrigation; and 3] growing certain crops in regions where the ET
requirements are lower and genetic potential of the crop can be realized.
2. REVIEW OF LITERATURE ON WATER PRODUCTIVITY IN IRRIGATED AGRICULTURE
Over the past few years, the concept of productivity of water in agriculture has gained ground owing to
increasing scarcity of irrigation water from physical and economic perspectives, mostly locally and often also
regionally. Several studies are available from the past which deal with water productivity of crops with respect
to evapo-transpiration (ET) of crops (see for instance, Table 1, Kijne et al., 2002: pp8 and Zwart and Bastiaanssen,
2004). But, we would discuss only those which are relevant for the present study.
Choudhury and Kumar (1980) and Singh and Malik (1983) showed large differences in water productivity
of wheat between wet and dry years. Tuong and Bouman (2002), estimated water productivity of rice in
India; found it in the range of 0.50-1.10 Kg./m 3 against 1.4-1.6 Kg./m 3 for wet-seeded rice in the Philippines;
1
See Allen et al., (1998) for definitions of consumed fraction (CF), non-recoverable deep percolation, non-beneficial evaporation,
consumptive use and ET, and differences thereof.
2
However, plants have highly developed adaptive mechanisms to compensate for water stress in different growth stages, and the only
way to factor these in properly is to use a well calibrated crop growth model, or through the development of crop production
functions.
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Oweis and Hachum (2002) analyzed water productivity impact of supplementary irrigation on pulses. Study by
Saeed and El-Nadi (1998) in Shambat, Sudan, Utao and Idaho on forage crops showed improvement in physical
productivity of water with supplementary irrigation. Rockström et al., (2002) provided evidence from Kenya
and Burkina Faso to the effect that supplementary irrigation enhances water productivity (Kg./m 3 ) of rain-fed
maize and sorghum, respectively, remarkably with greater effect coming with fertilizer management; and from
Tanzania to show that conservation tillage increases water productivity of maize.
Ahmad et al. (2002) used Soil Water-Atmosphere-Plant (SWAP) model to estimate water flux in the
unsaturated soil profile of groundwater irrigated areas of Pakistan Punjab under rice-wheat system and cottonwheat
system. Singh et al. (2003) used the same model to estimate the same for Sirsa district of Haryana. Both
the studies quantified the moisture changes in unsaturated soil profile during crop seasons. The studies found
that the vertical water flux in the unsaturated zone is continuous under rice-wheat system with frequent and
intensive irrigation. Though both the studies showed that a significant amount of the water applied is recycled,
they also showed significant build up of moisture in the unsaturated zone, which can be lost in soil evaporation.
It is recognized that the ET values themselves could reduce with better irrigation and soil management
(Burt et al., 2001), and thereby improving the chances of cutting down groundwater depletion. However, the
significance of achieving better groundwater balance through irrigation management increases with decreasing
efficiency of conveyance of percolating water from the crop root zone to the groundwater system. 3
Ahmad et al., (2004) estimated the spatial and temporal variations in water productivity (physical and
economic) separately for process evaporation, soil evaporation and actual ET which were estimated using SWAP
model for rice-wheat area in Punjab. They found that the applied water (sum of precipitation and irrigation) far
exceeded the evapo-transpired demand (ET) in case of rice causing deep percolation. Whereas, it fell short of the
ET requirements in case of wheat since some of the requirements were met by soil moisture depletion. They also
found that the process depletion (transpiration) to produce a unit weight of cereal was slightly lower for rice
when compared with wheat.
Abdulleev and Molden (2004) examined the issue of spatial and temporal variations in water productivity
in Syr Darya Basin in Uzbekistan and analyzed its economic and equity implications for basin water economy.
From the spatial analysis of water productivity, it was found that the water productivity for supplied water
(WP supply
) and potential evapo-transpiration (WP pet
) are higher for private farms. Water productivity of supplied
water is much lower than that of PET, indicating the scope for limiting water application. There is significant
difference in lowest and highest water productivities indicating the scope for increasing average water productivity
within the basin.
The temporal analysis of water productivity for paddy and cotton for three years (1999, 2000 and 2001)
showed the following: highest water productivity in case of cotton for both applied water and PET was obtained
in low rainfall years. It also showed that the difference between WP supply
and WP pet
was smaller in low rainfall
years, owing to the fact that irrigation water dosage was close to crop water requirement. In the case of paddy,
the highest water productivity (WP supply
and WP pet
) was obtained in 2001, which was a normal year and lowest
in 1999. Water productivity for paddy was not high during dry years.
Singh (2004) analyzed composite farming system in north Gujarat consisting of crops and dairying and
estimated productivity of applied well water in dairy farming. Kumar (2007) analyzed the composite farming
system in north Gujarat, to analyze the applied water productivity in dairy production. It also analyzed the extent
to which groundwater use in the region can be reduced without compromising on the farm economy and milk
production through efficient irrigation water use technologies using a simulation model based on linear programming.
To summarize, past research on water productivity were on analyzing average physical productivity of
water for select crops, including variation according to climate. There is limited analysis of marginal water
productivity (Kg./ET) in response to supplementary irrigation and change in depleted water. However, the
economic dimensions of water productivity were not analyzed. Analyses of incremental changes in water
3
The conveyance efficiencies would be low when the unsaturated zone is very deep due to loss of soil moisture through evaporation,
and non-recoverable deep percolation.
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productivity of crops in economic terms in response to changes in irrigation water dosage, or ET, were not
attempted. It is crucial to assess the potential for improving water productivity of a particular crop and deciding
on allocation priorities between crops.
3. OBJECTIVES OF THE STUDY
The objective of the study is to explore the scope for water productivity enhancement in irrigated
agriculture in India through: i] water control; ii] optimizing nutrient input to crop; iii] improving the quality and
reliability of irrigation water; and, iv] growing crops in regions where climate is favourable.
3.1 Hypothesis
1) Better reliability and adequacy of irrigation can improve yield and water productivity of irrigated crops
through better agronomic practices and better water management
2) Better control over water and fertilizers can ensure water productivity improvements in irrigated crops, as
water application regime might correspond to either ascending or descending water productivity response
curve to irrigation and nutrient inputs.
3.2 Approach and Methodology
The potential for improving water productivity through water control and optimum nutrient use is
assessed by estimating: 1] the incremental changes in water productivity (for select crops) with increase in
irrigation water allocation and fertilizer inputs. The potential for improving water productivity using climate
advantage is assessed by mapping the spatial variation in average productivity of crops vis-à-vis agro-climatic
regions. The potential for raising water productivity through improvement in quality and reliability of irrigation is
analyzed by comparing average water productivity with different sources of irrigation, which represent different
degrees of control over water delivery.
The regions of the study basins are shown in Map 1. The approach is that of primary surveys in the
study area. Three river basins in India were selected for the study. They are Indus; Narmada; and Sabarmati.
The study analyzed water productivity variations across: 1] farms growing the same type of crops with
same pattern of irrigation; and 2] irrigation sources (wells, canals and conjunctive use); and 3] agro-climates
within the same basin. It involved collection of data on parameters governing water productivity in crop production
such as cropping system, cropped area, crop inputs (bio and chemical fertilizers, farm labour, irrigation
water use, irrigation schedules, and crop technology), crop outputs (main product, by product, market price of
crops), and method of irrigation. For each irrigated crops, the sample size is 30-35 for each agro-climate within
a river basin. In addition, there were samples for each type of irrigation source. Hence, the maximum sample size
was 90 in one location; but limited to only situations where sufficient samples for different modes of irrigation
were available. The detailed sampling design is given in Table 1.
Table 1: Sampling Design for Water Productivity Study
Name of the Basin
No. of Locations
No. of Agro
climates
No. of Different
sources of Irrigation
Total Sample Size
Indus basin 3 3 3 (wells; conjunctive 200
use; canals)
Narmada 9 7 1 (wells only) 450
Sabarmati 6 3 1 (wells only) 180
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3.2.1 Data and Sources
Data used for water productivity analysis are primary data from farmers. Data collection was done
using a structured questionnaire from locations in all the four basins, viz., Indus, Narmada and Sabarmati. From
the Indus, only one location was covered; from Narmada, nine locations, each representing one agro-climatic
condition, was covered. From Sabarmati, four locations, each representing one agro-climate, were selected.
The data collected from farmers included: data on crop inputs comprising cost of seeds, labour, fertilizer and
pesticides, quantum of irrigation water, and quantity (weight in Kg.) and market price (Rs./Kg.) of main and
byproduct of the crop output. In addition, discharge of irrigation wells (litre/sec) was measured using a bucket
and stop watch to quantify the volume of water pumped, for which data on number and hours of irrigation for
each crop and for each season were obtained from the farmers.
3.2.2 Analytical Procedure
The physical water productivity (Kg./m 3 ) and water productivity in economic terms, θ
irri, i (Rs./
m 3 ) in a purely irrigated crop i are estimated as:
= ; ………………. 1, 2
, and are the irrigation water dosage (mm) and yield (Kg./ha.) for purely irrigated crop,
respectively in mm. is the net return per unit area of the crop (Rs./ha.). All winter crops selected for the
study are treated as purely irrigated crops, and the green j water use for these crops was ignored. The reason is
that their yields under un-irrigated condition as well as residual soil moisture before sowing are negligible. All
crops covering two seasons, viz., kharif and winter, having no rain-fed yields were also treated as irrigated
crops. Winter wheat in Narmada basin, cotton in west Nimar in Narmada basin, winter wheat in UP, Punjab, and
all crops selected from Sabarmati basin (namely, wheat, castor, bajra and cotton) were treated as irrigated crops,
and therefore the water productivity values estimated for them are irrigation water productivity. 4
Marginal physical productivity of water,
(Kg./m3), and marginal water productivity in economic
terms (Rs./m 3 ) for crops, which receive supplementary irrigation, and have rain-fed yields,
with respect to irrigation, are estimated as:
= ; = ……………… 3, 4
Where, is the yield corresponding to irrigation water applied (Kg.) and is the irrigation
water applied for the crop (mm).
is the net return per unit area corresponding to the
irrigation water applied for the same crop (Rs./ha). and were obtained by running a regression
of yield and net returns from the crop against irrigation water applied for each crop, respectively. The
regression coefficients give the marginal physical productivity of water and water productivity in economic
terms, respectively, of irrigation for these crops. This gives the mean value of marginal water productivity for all
4
In areas with moderate rainfall like eastern UP, this must have resulted in over-estimation of irrigation water productivity.
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the farmers growing that crop. One major assumption involved in this analysis is that the water application is still
in the scarcity regime, meaning the total consumptive use may fall short of or just meet the evapo-transpirative
demands. Therefore, the response curve of yield and net return to irrigation water use were treated as linear.
This no way means that the volumetric water applied (effective rainfall and irrigation) is below ET demand, as
farmers can provide excessive irrigation in certain periods of the crop season, resulting in losses.
The marginal water productivity of irrigation water for individual farmers were estimated by subtracting
the “a” coefficient , i.e., Y intercept, of the regression equation for yield and net return, respectively, from their
corresponding crop yield and net returns, and dividing by the volume of irrigation water applied. Paddy from
Jabalpur and Mandla in Narmada river basin were considered for this methodology, as it had rain-fed yield in
many locations.
4. SCOPE FOR ENHANCING IRRIGATION WATER PRODUCTIVITY IN AGRICULTURE
4.1 Using water control for improving irrigation water productivity
In order to assess the potential of “water control” in improving crop water productivity, the incremental
changes in crop yield and crop water productivity with respect to irrigation were analyzed. For this, the data
collected from four agro-climatic regions in Narmada river basin were analyzed. The analysis included the
following: 1] the crop yield response to irrigation water applied; 2] the water productivity (Rs./m 3 of water
applied) response to irrigation; and, 3] the yield response to fertilizer use.
In the case of Hoshangabad district, data of applied water, fertilizer dosage, crop yield, and water
productivity in economic terms (estimated) were available for two consecutive years, viz., 2002 and 2003. The
regression analysis showed that the relationship between dosage of irrigation water and yield for winter wheat of
2002 is linear. The R square value here is only 0.14, and hence the relationship is not strong. As shown in Figure
1, wheat yield responded to increase in dosage of irrigation water. However, for the same level of irrigation, the
yield differences across farmers are quite substantial. This can perhaps be explained by the difference in fertilizer
use by these farmers, differences in soil quality, changes in date of sowing, and differences in crop variety.
Figure 1: Yield vs. Irrigation Dosage in Wheat (Hoshangabad 2002)
Figure 2 shows the graphical representation of the variation in yield with differential levels of fertilizer
input. It shows a slightly stronger relationship between fertilizer use and crop yield (R 2 =0.16). Higher dosage of
fertilizer meant higher wheat yield. This does not mean that it is the higher fertilizer dosage, which caused higher
yield. Generally, it is the farmers who have good irrigation facilities and who use higher quantum of irrigation
water use proportionally higher dose of fertilizers. Due to this co-linearity between irrigation and fertilizer dosage,
the increase in yield cannot be attributed to higher dosage of fertilizers. Hence, in order to segregate the
effect of fertilizer dose on crop yield, a more thorough examination of data was carried out.
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Figure 2: Yield vs. Fertilizer Dosage (Hoshangabad 2002)
It was found that two farmers applying the same dosage of irrigation (1834 mm) applied different
quantities of fertilizers (worth Rs.1213/ha and Rs. 2160/ha, respectively) and got different levels of yield (19.8
quintal/ha and 31.7 quintal/ha, respectively). In another case, two farmers applied same dosage of irrigation
(2035mm), but applied fertilizers in varying doses (worth Rs. 975/ha and Rs. 1205/ha respectively), and got
different yields (1480 Kg./ha and 2500 Kg./ha respectively).
Figure 3: Water Productivity vs. Irrigation Dosage in Wheat (Hoshangabad 2002)
Figure 1 also meant that many of the farmers are applying scarcity irrigation and could have actually got
higher yield had they applied higher dozes of irrigation with proportional increase in fertilizer inputs. However,
the amount of water applied to the soil also influences the nutrient absorption capacity of the plants, and therefore,
irrigation water shortage might be limiting farmers’ ability to apply adequate quantities of fertilizers. Mostly,
the maximum yield corresponded to maximum irrigation.
The graphical representation of water productivity response to irrigation is given in Figure 3. The
relationship is inverse and exponential. Higher dosage of water applied meant lower water productivity
(R 2 = 0.28). Generally, those who applied higher dosage of water had lower levels of water productivity, while
many farmers who applied lower dosage of irrigation (200 to 225 mm of irrigation) got high water productivity.
At the same time, many farmers who maintained similar dosage of irrigation got much lower water productivity
(Rs./m 3 ). This could be due to the lower levels of fertilizer inputs, which reduced the crop yields. The lower
water productivity at high dosage of irrigation could be due to lack of proportional increase in yield, increase in
cost of fertilizers which reduces the net returns, and increase in volume of water applied, which increases the
value of denominator.
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The analysis was repeated for the 2003. It showed a stronger positive linear relationship between
applied water and crop yield in wheat (R 2 =0.21). Higher levels of water dosage generally ensured higher yield
(Figure 4). The incremental yield due to increase in dosage of irrigation by 100 mm was around 230 Kg./ha.
Again, there were significant yield differences between farmers who applied more or less same amount of water.
This could be explained by the factors mentioned above. Nevertheless, slightly improved relationship better
fertilizer and irrigation dosage (with an R 2 value of 0.25) confirms to this (Figure 5).
Figure 4: Yield vs. Irrigation in Wheat (Hoshangabad-2003)
Now, the regression values for the response of yield to irrigation dosage being very small (Figure 1 and
Figure 4). So, one could argue that many factors other than irrigation explain yield variations. But, given that the
data presented here are for different farmers, who represent different soil conditions, different planting dates and
different seed varieties, all of which have a potential to influence the crop yield, the relationship and regression
coefficient is significant5 . Also, the slope of yield curve is very mild in the case of Figure 3, which is quite
contrary to what can normally be found given the wide range in irrigation water dosage among the sample
farmers.
Figure 5: Yield vs. Fertilizer Dosage in Wheat (Hoshangabad-2003)
The regression between water dosage and water productivity (Rs./m 3 ) showed a poor inverse relationship
between the two unlike what was found for 2002 (Figure 6). This could be due to the reasons explained
above for the same crop grown during 2002. Some of the farmers who were in the lower range of irrigation
dosage (between 200 mm and 300 mm) got very low water productivity values (between Rs. 0.41/m 3 and Rs.
1.38/m 3 ), while some other farmers got values of approximately Rs. 7/m 3 of water. This could be due to the wide
differences in fertilizer dosage, which resulted in differential yields. The strong linear relationship between
fertilizer dosage and crop yield (R 2 =0.25) are shown by Figure 5.
5
With changing soils, the nutrient levels could change. With changing planting dates, the soil moisture availability could change; so the
crop water requirement and yield potential. Yield potential could also change with seed variety.
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A closer look at the chart showing relationship between irrigation dosage and crop yield also provide
better clues to this effect. There are many examples of farmers applying similar dosage of irrigation, but different
dosage of fertilizers and getting different levels of yield. For instance, two farmers who applied irrigation
dosages of 2518 and 2557 m 3 of water to their wheat, applied different levels of fertilizers (worth Rs.1112/ha and
Rs. 2400/ha) and in turn got yields of 2910 Kg/ha and 4000 Kg/ha, respectively.
Figure 6: Water Productivity vs. Irrigation Dosage in Wheat (Hoshanganad-2003)
The analysis was repeated for west Nimar in Narmada basin, for cotton for 2003. After the rainy
season, the crop is normally irrigated. The yield response to irrigation was polynomial (Figure 7), with yield
increasing up to a point (from 100mm to 300mm), and then declining. Many farmers who applied close to 300
mm got highest yields. Beyond 300mm, the yield started declining. The curve showing the water productivity
(Rs./m 3 ) response of irrigation dosage (Figure 8) is again “polynomial”. With increase in dosage of irrigation,
while the yield increased, the water productivity did not get affected much. But, beyond the point of optimum
yield, increase in irrigation dosage led to declining water productivity. This is the third set of response curves
(Figure 7).
Figure 7: Yield vs. Irrigation Water Dosage in Cotton (West Nimar 2003)
The foregoing analyses show that water productivity can be manipulated through water control. It is
based on the premise that in many situations farmers do not have control over water delivery and fertilizer
dosage, or are tempted to apply more water to maximize yields and returns per unit of land. In the process, they
are not able to get the optimum yield that gives highest water productivity. 6 To what extent “water control”
would help enhance water productivity depends on that point of yield and water productivity response curve to
which, the irrigation dosage corresponds. It would also depend on what fraction of the applied water from the
crop is used for non-beneficial evaporation. We do not have any information about non-beneficial depletion from
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applied water. Some of the sources are: a] the deep percolation, which is lost in the vadose zone; 7 b] the
evaporation of soil moisture after crop harvest during the fallow period; c) direct evaporation from the soil
surface, especially during crop establishment and d) possibly un-necessary watering at the end of the season
when it does not contribute to yield.
There are three different types of responses of yield and water productivity to irrigation dosage. In the
first situation: a] the relationship between applied water and yield is positive, but weak; and b] the response of
WP to applied water is inverse and exponential. In such situations, the reduction in dosage of irrigation water
would not affect the yield significantly; and often the effect may not even be adverse. The same would significantly
enhance WP. However, this strategy would work only if there is sufficient arable land, which remains
uncultivated due to shortage of water. The reason is that farmers would like to expand area under irrigation and
use the water saved from field to irrigate additional land to maintain income returns.
The second situation is one in which the relationship between applied water and yield is strong and
positive, where in most farmers are applying water under scarcity regime and very few under water abundance
regime (Figure 4, 5 and 6). It is likely that with increase in dosage of irrigation, the physical productivity of water
also might increase slightly. However, the response of water productivity in economic terms (Rs./m 3 ) to applied
water is “inverse-logarithmic”. Here, the best strategy for most of the farmers would be to minimize the irrigation
dosage, which would help obtain highest water productivity in economic terms. Here, it may be necessary
for the farmers to expand the area under irrigation slightly to maintain the net returns.
Figure 9: Potential Changes in Crop Yield and Water Productivity under Micro Irrigation
In the third situation, the relationship between applied water and yield is “polynomial”, where yield
increases with irrigation dosage up to a certain point, and then declines (Figure 7). In such a case, with increasing
dosage of water, water productivity declines abruptly beyond the point, which corresponds to the maximum
yield. Hence, the relationship between applied water and water productivity in economic terms is “polynomial”
(Figure 8). This is the ideal situation where farmers who are losing on the yield and income returns have an
incentive to reduce irrigation dosage. By doing this, they enhance both yield and water productivity. The reason
6
Water productivity is not an objective for farmers to realize when water is in plenty. On the contrary, they would try and maximize
the income returns per unit of land, for which crop yield (Kg./ha) enhancement is the best route.
7
Water “lost in the vadose zone” normally becomes non beneficial E or ET as bare soil evaporation or transpiration through other
(non-productive) vegetation.
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for over irrigation of crop beyond the point of maximum return is zero marginal cost of electricity used for
groundwater pumping owing to flat rate system of electricity pricing in the regions under study. In such situations,
it is not even necessary that farmers expand the area under irrigation to maximize their aggregate returns
from farming. There are many farmers, who are not getting optimum yield and water productivity due to
inadequate irrigation dosage. It is important for them to reduce the area under irrigation while increasing irrigation
dosage to save water8 .
Now, let us look at the option of micro-irrigation. For a given amount of nutrient inputs, the only
determinant of crop yield is ET and how far the transpirative requirements of the crop area met during critical
stages of crop growth. Under micro irrigation, non-recoverable deep percolation is negligible. Further, the nonbeneficial
evaporation of applied water can be reduced to nil, particularly for row crops. Such non-beneficial
depletion, which is the difference between CF and crop ET (Allen et al., 1998), would be much less as compared
to traditional method of irrigation, more so for row crops. It is possible to achieve the twin-objectives of
higher water productivity and higher yield through micro-irrigation. The theoretical response curve of yield (Kg./
ha) and water productivity in economic terms (Rs./m 3 ) to irrigation dosage under traditional irrigation and micro
irrigation is given in Figure 9. It shows that the yield corresponding to the same amount of “applied water” would
be higher under micro irrigation. Research in many parts of India had already shown that for cash crops,
particularly those grown in rows such as cotton, the net incremental returns for drip irrigation plots over flood
irrigated plots are higher than the sum of capital and operational costs of drip systems (Narayanamoorthy,
2004). 9 This means that even in situations where the entire land is irrigated, farmers might have incentive to go
for micro irrigation for such crops. The water productivity gain automatically comes under such situations.
4.2 Improving irrigation water productivity through optimizing input use
In order to assess the potential of “optimum nutrient dosage” in improving crop water productivity, the
incremental changes in crop yield and crop water productivity with respect to fertilizer dosage were analyzed.
For this, the data collected from four agro-climatic regions in Narmada river basin were analyzed. The analysis
included the following: 1] the yield response to fertilizer application; and 2] the water productivity response to
fertilizer application.
As regards yield response to fertilizer inputs, in the case of wheat in Hoshangabad, it was found that
response is extremely weak for the drought year (2002) as shown in Figure 2 (R 2 =0.16). At the same time, the
response was reasonably good for the normal year 2003 (R 2 =0.25) as shown in Figure 5. Water productivity
was also higher for farmers who applied higher dosage of fertilizers (R 2 =0.27) in 2003, though such trends were
not seen for 2002 which was a drought year. Figure 10 shows the response curve of water productivity to
fertilizer input across the farmers. Such a response does indicates that farmers are optimally using fertilizers and
irrigation water to enhance the returns.
In case of cotton crops in West Nimar, water productivity response curve for fertilizer dosage was
“polynomial” for 2002 (drought year) with productivity (Rs./m 3 ) increasing from the lowest values at low levels
of fertilizer use towards the middle range, and then declining (R 2 = 0.11). Such a response curve can be explained
this way. Very high doses of fertilizers is generally accompanied by increased dose of irrigation water. Higher
dosage of irrigation water could also increase the chances of fertilizer leaching, reducing the nutrient intake by
the plants and flattening the response curve of yield. At the same time, the yield gains obtained due to the same
were not significant to offset the effect of increased cost of inputs, and increase in the volume of water applied.
This is quite natural as the farmers are interested in maximizing the returns pet unit of land, and not water.
Figure 8: Water Productivity vs. Irrigation Water Dosage in Cotton in West Nimar- 2003
9
Such crops include banana, sugarcane, orange, grapes and cotton.
9
But, cases where farmers are not able to secure optimum levels of water productivity due to water shortages are rare. Well owners
have reasonably high degree of control over water delivery. Power supply is the only factor that reduces their water control. In states
such as Punjab, Gujarat and Madhya Pradesh, quality of farm power is poor. The supply is provided in rotations, including during
night. This might affect the dosage of water farmers could give to crops in hard rock areas with limited groundwater.
131

For a “linear response curve” of yield to fertilizer dosage, the response curve for water productivity
(Rs./m 3 ) may not be inverse exponential or inverse logarithmic; but “direct and linear” as shown in the case of
wheat in Hoshangabad for 2003 (Figure 10). Inverse relationships can occur only if the fertilizer dosage is
accompanied by increased dosage of irrigation. With increase in fertilizer dosage, the water productivity could
actually rise, and then decline. This is because it would be possible to increase yields with increase in fertilizer
dosage, without much change in irrigation dosage up to certain point. Beyond this point, increased use of
fertilizer dosage would require greater dosage of irrigation for increasing the nutrient absorption capacity of the
plants. This may not result in increase in ET, thereby showing no effect on crop yield. However, this would
reduce water productivity as the total depletion or CF would increase. Here adjusting the fertilizer dosage to
optimal levels is crucial.
Figure 10: Water Productivity vs. Fertilizer Dosage in Wheat (Hoshangabad 2003)
For the same dosage of irrigation water, crop yield can be enhanced to an extent with optimal dosage of
fertilizers. This means that the physical productivity (Kg/m 3 ) of water, apart from returns from land, can be
enhanced through manipulation of fertilizer use. 10 This might increase water productivity in economic terms as
well (as seen in the earlier section). Such situation may be encountered in central India (covering most parts of
Narmada, Tapi, Mahi and Krishna basins), where fertilizer use in agriculture is one of the lowest. If fertilizer
dosage does not increase the yield, then simple reduction in dosage would result in saving of input costs, thereby
10
Primary data collected from farmers in Narmada basin show that with increase in irrigation dosage, there is proportional increase in
the dosage of fertilizers in most situations. Hence, the effect of fertilizer on crop yield and water productivity cannot be assessed
through multiple regression model estimation procedures.
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increasing water productivity in rupee terms. Such situations are possible in Punjab and Haryana where application
of nitrogenous fertilizer is excessively high.
4.3 Improving water productivity through improving quality & reliability of irrigation water
There is not much empirical evidence to suggest that greater reliability and quality of irrigation leads to
greater water productivity.
Analysis from groundwater irrigated areas of north Gujarat showed that the gross returns per cubic
metre of applied water was higher for shareholders of tube well companies, when compared to farmers who
were buying water from well owners. The gross water productivity was Rs. 5.61/m 3 for tube well owners
against Rs. 4.61/m 3 for water buyers. The gross returns only indicate the physical efficiency of water use. It
does not take into account the input costs, and only converts the main product and byproduct into cash equivalents.
In the case of shareholders, the entitlement of water is fixed in volumetric terms, and water supply is
highly reliable. In case of water buyers, the well owner supplies enough water to make sure that the cultivator
gets sufficient yield as his irrigation charge is paid in proportion to the total crop yield.
The difference between the two cases is in terms of water allocation norms and reliability of water
supply. In the case of shareholders, supply is rationed and known to the farmers much in advance of the season.
Hence, they are able to do proper water budgeting and apply optimum dosage of fertilizers. Whereas the farmers
who purchase water on hourly basis are at the mercy of the well owners. They do not try to optimize fertilizer
dosage or go for the best quality seeds, as they are not sure of getting adequate water supplies. This reinforces
the fact that net return from crop production is less elastic to the cost of irrigation than the reliability of irrigation.
Yields in two major crops, viz., wheat and paddy in three different types of irrigation systems, which
represent three different degrees of water control, in two different regions of Bist Doab area in Punjab, were
compared to understand the impact of differential quality of irrigation water. The three systems selected are
canal irrigation, well irrigation and conjunctive use. The underlying premise was that canal irrigators will not be
able to apply water at critical stages in right quantities, whereas well irrigators would be able to apply water to
their crops as and when they require, subject to the availability of electricity. As farmers using both canal water
and well water should have a higher degree of control over water application compared to canal irrigators, the
“overall quality of irrigation” would depend on what proportion of the total demand is met from canals, and what
proportion from groundwater.
Analysis involved comparing water productivity in wheat under different sources of irrigation in two
distinct agro-ecological regions. Adequate numbers of irrigators for each of the three sources of irrigation were
not available from the same agro-ecological region. The first is lower Bist Doab area, with low rainfall and semi
arid climate; and the second the sub-mountainous region with medium to high rainfall with sub-humid climate.
Comparison of yield with different sources of irrigation was made between conjunctive use and canal water (in
sub-mountainous region). The analysis showed that yield figures are lowest for farmers using only canal water
for both paddy and wheat; second lowest for farmers using both canal water and groundwater (Table 2). The
farmers using well water (in Jalandhar and Kapurthala) got the highest yield. The yield differences between
categories within the region and across regions are substantial. While agro-ecology would be an important factor
affecting the crop yields, such large differences in yield could only be explained by the quality and reliability of
irrigation water.
The foregoing analyses clearly show that improvement in quality and reliability of irrigation would
impact yield significantly. Here, quality of irrigation includes adequacy and reliability. With greater reliability and
adequacy of irrigation, farmers would be able to adopt good agronomic practices and adjust nutrient use. Enhanced
quality and reliability of irrigation would also help farmers optimize the irrigation dosages in each watering
and give adequate number of watering including watering at critical stages of plant growth. This would not
only increase the yield, but also reduce non-beneficial depletion.
Table 2: Differential Land Productivity with varying quality of irrigation in Punjab
133

Name of District Predominant Source
Name of Region Paddy Wheat
of Irrigation Crop Yield (ton/ha)
6.26 4.68
Jalandhar
Well Water
5.20 4.40
Lower Bist Doab
5.98 4.73
Kapurthala
Well Water
5.52 5.30
4.46 3.82
Conjunctive Use
4.65 3.79
Sub Mountainous Hoshiarpur
Canal Water
2.77 3.52
3.47 2.80
Source: Authors’ own analysis using primary data
Whereas with uncertainty in irrigation schedules and water delivery, as found in the case of canal
irrigation, farmers hesitate to apply adequate quantities of fertilizers, thereby losing yield. In many cases, the
depth of each application is much higher than the optimum dosage determined by the capacity of the field with
uncertainty of water supply as compared to assured water supply (well water). This leads to heavy percolation
losses and excessive residual moisture after harvest. These cause increase in non-beneficial depletion over crop
ET. Greater irrigation dosages may also increase fertilizer leaching, reducing nutrient use efficiency.
4.4 Enhancing irrigation water productivity using climatic advantages
The spatial analysis of water productivity is an important aspect of the strategy to enhance water
productivity at the agro-climatic level (Kijne et al., 2002: page 13), as productivity of applied water is a function
of agro-climate (Abdulleev and Molden, 2004). Spatial analysis of water productivity of selected crops was
carried out for nine districts falling in seven agro-climatic regions in Narmada basin, and three agro climatic
regions in Sabarmati river basin (Table 3 and Table 4). Theoretically, climate can influence both physical productivity
of water and water productivity in economic terms. The climate determines the actual consumptive water
requirements and potential crop yields, and the availability of soil moisture from precipitation. In regions, with
favourable climatic conditions, the biomass output per unit of water evapo-transpired would be higher. Here, we
have compared water productivity of wheat and paddy, which are two significant crops.
The physical productivity of applied water for grain production during the normal year was estimated to
be highest for Northern hill region of Chhattisgarh in Mandla district (1.80 Kg./m 3 ) although Raisen falls in the
traditional wheat-growing belt; it was lowest for Jabalpur in Central Narmada Valley (0.47 Kg./m 3 ). This is
mainly due to the major difference in irrigation water applied, 127 mm in Mandla against 640 mm in Jabalpur.
This is a significant difference, with the highest being 250% more than the lowest. The difference in irrigation
can be attributed to the difference in climate between Jabalpur (dry semi-humid) and Mandla (moist sub-humid),
which changes the crop water demand. It can also be noted that the physical productivity in normal year is
second highest in Raisen (1.01 Kg./m 3 ). Higher biomass output per unit volume of water (physical productivity)
should also result in higher economic output especially when the difference is mainly due to climatic factors,
which changes the ET requirements, unless the factors which determine the cost of inputs significantly differ. In
our case, it was found that the net economic return per cubic metre of water was highest for the same region for
which physical productivity was higher (Rs. 4.09/m 3 ). The same was lowest for Narsingpur (Rs. 0.86/m 3 ),
which had the second lowest physical productivity.
The difference between gross and net water productivity (furnished in Table 3) is that in the first one,
the total economic value of outputs from unit area of outputs is only considered in the numerator, whereas in the
134

second case, the net income from crop production after deducting the cost of inputs per unit area is considered.
Table 3: Region-wise Irrigation Water Productivity (Wheat) and Marginal Productivity of Irrigation Water (Paddy)
in Narmada River Basin for Selected Crops
Name of the Region
Name of the
District
2002-03 (Drought Year) 2003-04 (Normal Year)
Physical
Productivity
(Kg./m 3 )
Wheat
Hoshangabad 0.81 0.81 5.74 2.09 0.91 0.90 6.25 2.31
1. Central Narmada Valley Jabalpur 0.44 0.43 3.08 0.89 0.47 0.46 3.42 1.06
Narsingpur 0.53 0.49 3.84 1.11 0.49 0.47 3.47 0.86
2. Jhabua Hills Jhabua 0.73 0.65 5.32 1.38 0.60 0.55 4.69 1.20
3. Satpura Plateau Betul 0.72 073 5.34 2.14 0.84 0.82 6.05 2.61
4. Malwal Plateau Dhar 1.07 1.02 8.05 2.46 1.05 1.05 7.67 2.04
5. Nimar Plain West Nimar 0.85 0.83 6.65 2.38 0.83 0.83 6.20 1.99
6. NHRC Mandla 0.92 0.88 6.62 1.44 1.80 1.78 12.75 4.09
7. Vindhya Plateau Raisen 0.77 0.77 5.33 2.00 1.01 1.01 6.82 2.77
Paddy
1. Central Narmada Valley Jabalpur 1.08 0.79 5.86 1.99 1.62 1.15 9.36 3.95
2. NHRC Mandla 1.74 1.26 11.69 2.12 2.13 1.59 12.50 1.43
NHRC: Northern Hill Region of Chhattisgarh
Source: authors’ own analysis based on primary data
There are only two regions in Narmada basin, which irrigate paddy. The physical productivity for grain
during the normal year was higher for Northern hill region of Chhattisgarh in Mandla district (2.13 Kg./m 3 ) while
it was only 1.62 Kg./m 3 in Jabalpur district of Central Narmada Valley. Likewise, water productivity in economic
terms was higher for Northern hill region of Chhattisgarh (Rs.3.95/m 3 ) against Rs. 1.43/m 3 for Jabalpur, in
Central Narmada Valley. Similar figures were found for the drought year (2002) in which the physical productivity
of applied water was 1.74 Kg./m 3 in Mandla against 1.08 Kg./m3 in Jabalpur.
Similar patterns of variation in water productivity across agro-climates were found in Sabarmati rive
basin also. The physical productivity of water for wheat ranged from 0.71 Kg./m 3 in Daskroi to 2.75 Kg./m 3 in
Bayad. The water productivity in economic terms (gross) ranged from Rs. 4.66/m 3 in Daskroi to Rs. 18.39/m 3
in Bayad, and the net water productivity from Rs. 1.38/m 3 to Rs.4.66/m 3 . Similar variations in physical productivity
of water were found for castor oil between Himmatnagar and Kapadwanj. The physical productivity of
water ranged from 0.66 Kg./m 3 to 1.62 Kg./m 3 . The gross economic water productivity ranged from Rs. 9.69/
m 3 in Himmatnagar to Rs. 25.57/m 3 for Bayad. The net economic water productivity ranged from Rs. 3.56/m 3 in
Himmatnagar to Rs. 16.4/m 3 for Bayad. Interestingly, unlike in the case of wheat, the locations which gave
highest economic water productivity did not coincide with that of highest physical productivity of water in case
of castor oil.
Synthesis of results on crop water productivity in Narmada basin and Sabarmati basin show that the
variation in water productivity of irrigated crops across regions is mainly due to variation in agro-climate, which
135
Water Productivity
in Economic
Terms (Rs./m 3 )
Gross
Net
Physical
Productivity
(Kg./m 3 )
Water
Productivity
inEconomic
Terms(Rs./
m 3 )
Main By-
Product Product
Main By-
Product Product Gross Net

educes the crop water requirement. The northern hill region of Chhattisgarh has moist sub-humid to dry-subhumid
climate. The four regions, viz., Kymore plateau and Satpura hills, Vindhya plateau, Satpura plateau and
Central Narmada Valley (CNV) have “dry sub-humid” climate. The regions, viz., Malwal plateau, and Nimar plain
have semi arid climatic conditions. The district of Jhabua, which falls in the region, named “Jhabua hills”, is
“semi arid”. .11 The question therefore is: whether the natural advantage, which certain crops enjoy in certain
regions in terms of higher water productivity by virtue of the agro-climate can be made use of, without compromising
on farmers’ need and priorities. This means, earmarking certain crops only in those regions where they
have relative advantage of high water productivity-both physical and combined (physical and economic).
5. POTENTIAL FOR IMPROVING IRRIGATION WATER PRODUCTIVITY IN INDIA
5.1 Crops and areas for increasing Irrigated water productivity
Regions which receive intensive canal irrigation are regions that should get priority in water productivity
improvements because: 1] the water-intensive crops are grown in these regions; 2] there is poor control over
water delivery, and 3] quality and reliability of irrigation is poor. Semi arid and arid regions with deep water table
conditions are ideal for water productivity enhancement (reduction in non-beneficial evaporation and non-recoverable
deep percolation). Semi arid Punjab and Haryana are known for intensive cropping of wheat and paddy,
which have ample scope for improving yield.
After canal irrigated areas, areas that depend on well irrigation and where substantial area is still left uncultivated
due to water scarcity should receive attention. The reason is that under such situations, the farmers
can expand the area under irrigation and increase aggregate returns. The priority areas would be hard rock areas
of peninsular, central and western India. The water-intensive crops grown in large areas in this region are paddy,
cotton, sugarcane, banana, cotton, castor, groundnut, and potato (Kumar and Singh, 2006).
Row crops such as cotton, groundnut, potato, castor, banana and sugarcane can also be prioritized for
water productivity improvement. Here, it can come from the use of micro irrigation devices, especially in sandy
soils, as it is very difficult to maintain high distribution uniformity in water application with traditional method of
irrigation such as level borders and furrows. Large-scale adoption of drip irrigation for banana and sugarcane in
Maharashtra and for potato, groundnut, cotton and castor in north Gujarat serve as successful examples.
5.2 Potential improvements in water productivity and water saving at the basin level
The gain in applied water productivity through “water control” results in same extent of gain in
productivity of depleted water only in semi-arid and arid regions where the depth to groundwater table is large, 12
and where non-beneficial evaporation from fallow land is high. In such regions, a significant portion of the
applied water depletes. Hence, there can be basin level productivity gains through control over water delivery. 13
However, for farmers to adopt water control measures, they must have extra land to bring under irrigation. This
is because the net return per unit area might decline due to water control measures. At the aggregate level, there
would be no reduction in the demand for water.
Though micro irrigation would raise crop water productivity both in physical and economic terms
without reducing yield (as illustrated by Figure 11). The impact of micro irrigation would be significant in arid
and semi arid areas, and for row crops. This is because in case of row crops evaporation component of
consumptive use of water by crop (ET) is quite large, especially under aridity conditions (Kumar et al.,
forthcoming). The area under row crops is very small in the sub-humid and humid areas and water abundant
areas.
11
See Kumar and Singh (2006) for detailed description of average annual rainfall and reference evapo-transpiration in all the nine agroclimatic
regions falling in Narmada basin.
12
Deep groundwater table and aridity means that the return flows from applied water are not significant; and evaporation of residual
soil moisture from fallow is very high.
13
In other regions—sub-humid and humid regions with shallow groundwater, the basin level water productivity gain would be very
much lower.
136

Peninsular India and Western India have substantial area under crops that are conducive to micro
irrigation technologies; north and central India has very little area under such crops with the exception of Uttar
Pradesh. Western part of Mahanadi is another area that would be conducive to water saving technologies (WST).
Use of micro irrigation system can significantly reduce crop water demand per unit area of cultivated land in
semi-arid and arid area, with deep groundwater table conditions or with saline aquifers. However, in these areas,
farmers use the saved water to expand the area under irrigation to maximize their aggregate returns (if uncultivated
land is available). As a result, the aggregate demand for water may not change. However, areas where
intensity of irrigation is already highest like in central Punjab and Haryana might be exceptions.
The basins that are conducive to measures for improvement in water productivity through water control
are: 1] all east-flowing rivers of peninsular India; 2] rivers north of Tapi in Gujarat and Rajasthan; Mahanadi;
some parts of Indus basin covering south-western Punjab; and 3] west- flowing rivers of South India. This is
because these basins fall under semi arid and arid climatic conditions, and have moderately deep, to deep groundwater
levels. These basins have very large areas, which are un-irrigated due to limited availability of groundwater
and canal water. Hence, farmers would have incentive to improve water productivity. In the process, they would
be able to maximize the aggregate returns.
There are some regions in India where water productivity is not a consideration for individual farmers.
The economy here would benefit a lot by reducing the amount of water depleted and the energy used up in
growing crops. Such areas include parts of Indus in central Punjab, Haryana and UP, which are groundwater
irrigated. In such areas, water productivity improvement measures can help raise income returns from every
unit of land irrigated. The only option to enhance water productivity is water delivery control. It can be used
effectively in such situations where excessive irrigation leads to yield losses.
In Punjab and Haryana, improving adequacy and reliability of canal water supplies would lead
to greater yield for wheat and paddy, apart from reducing non-beneficial depletion and improving water productivity.
Hence, irrigation departments should have incentive to go for improving both quality and reliability of
irrigation water, and “water control”. Since there is no scope for exploding groundwater-irrigated area, it would
lead to reduction in groundwater draft as well.
6. POLICY ALTERNATIVES FOR IMPROVING WATER PRODUCTIVITY
It is widely recognized that flat rate mode of pricing of electricity resulted in inefficient, and unsustainable
use of groundwater (Kumar and Singh, 2001; Kumar, 2005). Pro-rata pricing of electricity would create
direct incentive for efficient water use as it induces positive marginal cost of water application. There will be two
different outcomes of this policy change: 1] as the marginal cost of using electricity is positive, farmers would
adopt water abstraction systems that are more energy efficient, which means the electricity used for pumping
and applying a unit of water would be less, so the marginal cost of increasing the dosage of water; and 2]
farmers could increase water use efficiency in crop production, enhancing physical efficiency (Kumar, 2005).
By enhancing water use efficiency, the farmer can reduce the water application to their crops, as the net
marginal returns would become negative at original level of water dosage. Such reductions in applied water will
be affected without any change in the consumptive use through better farm water management and better
conveyance methods. Farmers can also adopt drip irrigation systems that require low energy to run, 14 which
also save energy. There would be no adverse effect of reduced irrigation dosage on yield. Instead, the irrigationnet
water productivity curve itself would shift diagonally upwards due to slight improvement in net water
productivity.
In the long run, total metering and pro-rata pricing would be the most desired scenario, The government
can start with metering of agricultural consumption. Heavy subsidy for WSTs can be provided to farmers who
are willing to use meters, provided they minimize electricity consumption. It could reduce with increase in total
energy consumed, and increase with increase in percentage cropped area under water-saving irrigation technol-
14
Like micro tubes and sub-surface drip irrigation systems (porous pipes). For details please see Kumar, Singh,
Sharma and Amarasinghe (2007).
137

ogy. This can help realize the twin objective of more efficient and sustainable groundwater use, and efficient
energy use.
In groundwater irrigated areas, improving power supply conditions – both quality and hours of supply
– is extremely important for achieving greater control over water delivery. Unreliable power supplies and power
supply during night time force farmers to apply excess water whenever power supply is available (Kumar and
Singh, 2001), instead of application at the critical stages of crop growth that gives higher productivity. This leads
to inefficient use from both physical and economic points of view as shown by a study in Mehsana. In canal
command areas, farmers should be provided with subsidies for storage systems and small pump sets. This
would result in greater control over “water delivery” and better quality of irrigation to achieve higher water
productivity in physical and economic terms.
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